Descriptions of a large number of pulling and holding devices appear in the prior art, examples of which are those mechanisms identified as cargo holddowns, scaffold supports, chain tighteners, chain hoists and wire stretchers.
In common with applicant's structure, many of the prior art disclosures describe devices utilizing sprocket wheel chain combinations, in most of which the chain moves along a nonlinear path, requiring an unsymmetrical housing to conform to the curving path of the chain. Further, most of the prior art mechanisms are intended for heavy duty operations and the necessary strength of the structural members requires correspondingly heavy and cumbersome components.
It has been found that an effective pulling and holding chain gear device, sufficiently small in size and weight for convenient use by sportsmen, for example, may be fashioned from a minimum of parts into a simple structure by the utilization of certain of the parts to perform two or more essential functions. Among the uses for such a light weight device are compound crossbow stringing, and chain tightening and holding for the purpose of securing a hunter's seat to the trunk of a tree.